Impeller construction for rotary pressure pumps



Dec. 21, 1954 LlNDQUlST 2,697,402

IMPELLER CONSTRUCTION FQR ROTARY PRESSURE PUMPS Filed Sept. 15, 1950 ARTHUR ZS [IL v22 U/sz' I N V EN T OR.

- [from/115k United States Patent Office 2,697,402 Patented Dec. 21, 1954 IMPELLER CONSTRUCTION FOR ROTARY PRESSURE PUMPS Arthur E. Lindquist, Bellflower, Calif. Application September 15, 1950, Serial No. 184,967 2 Claims. (Cl. 103-126) This invention relates to an impeller construction for rotary pressure pumps.

More specifically speaking, this invention pertains to an impeller of the above stated kind which is encased in an elastic jacket in such a manner as to produce a constant fluid tight seal between said impeller, the pump casing and a co-operating impeller, thus causing the pump to be of a self priming character and insuring therefor a positive suction, as well as a positive discharge.

Among the objects of the present invention are; to provide a rotary pump impeller which will act in a more positive and power economizing manner upon any fluid to be pumped; to provide a durable and satisfactory jacket for the impeller, which will efliciently function for a long period of use; and to provide, with a view to carrying out the preceding object, an elastic impeller jacket that will utilize a rubber or rubber like material in a more practical and eflicient manner for the aforesaid constant fluid sealing purpose.

It is also an important object of the invention to provide a rotary pump structure wherein the erosive eifect of abrasives in the liquid being pumped is reduced to a minimum, the resilient, compressive nature of the jackets for the rotary impellers, provided by this invention, being of particular advantage in fluids containing sand, grit, solids and abrasives.

A more specific, additional object is to provide, in a rotary pump having an oil containing gear housing abutting the pump chamber, a means for jacketing the rotary impellers in such a manner as to prevent water leakage around the impeller shafts from the pump chamber into said gear housing.

By this invention a pair of intermeshing toothed impellers are provided which have metallic body portions which are of a durable, inflexible character, and each of these impellers is furnished with an elastic rubber jacket. This combination lessens drag due to impeller distortion under strain (which occurs in impellers having rubber body portions), and at the same time provides a force pump capable of ejecting liquid at a very high pressure per square inch, for example, as high as 500 pounds, in an ordinary sized pump.

The invention includes a pair of intermeshing, toothed pump (or motor) impellers wherein either one or both of said impellers carries an elastic jacket which may cover only the periphery of its toothed portion, or may also cover one or both of the end portions of such impeller; in combination with inlet and outlet passages for the rotor chamber with diameters equal to or greater than the distance between the axes of the pair of intermeshing rotors in said chamber, the axes of said inlet and said outlet passages alining and extending at a right angle to said shafts in a plane parallel to and located midway between them, the diameters of said inlet and outlet passages being constant.

Also it is an object of the invention to provide an impeller construction for a rotary pump, which, in combination with novel feed and discharge passage means, is capable of handling, without becoming clogged, liquids heavy laden with sediment, such as sludge in tank bottoms, straw mixed with cow manure, fish, and crushed kelp, this being done with a three inch pump.

Other objects, advantages and features of invention will hereinafter appear.

Referring to the accompanying drawing, which illustrates a preferred embodiment of the invention as now being manufactured,

Fig. l is a side elevation of the pump, interior structure being indicated by dotted lines.

Fig. 2 is a vertical, longitudinal mid-section on line 2-2 of Fig. 3 with some cylindrical parts shown in elevation.

Fig. 3 is a view partly in end elevation and partly in vertical cross section.

Referring in detail to the drawing, the casing comprises a body portion 10 which is elliptical as viewed in cross section, with the long axis of the ellipse extending vertically. One side of said casing body 10 is provided with a circular intake extension 10a and the opposite side thereof is provided with a like outlet extension 10b. Also, one end of said body portion 10 is closed by an elliptical head 11 having a peripheral flange 12 bolted to a like flange 13 carried by the adjacent portion of said casing body 10. At its lower end said head carries an integral, angular foot which the pump rests.

Against the end thereof opposite to its said head 11, said casing body 10 has abutting against it an elliptical head 16 shown as substantially a twin to the aforesaid head 11, being likewise provided with a peripheral flange 17 which mates with a peripheral flange 18 around the adjacent end of the pump body 10. Against the outer side of said flange 17 abuts the flange portion 19 of a cup shaped cap 21, said flange portions 17, 18 being suitably apertured to receive bolts 22 whereby the cap 21 is secured to the pump body 10 with the head 16 interposed between said cap and pump body.

The invention pertains more particularly to the construction of the intermeshing, gear toothed impellers 25 and 26 each of which is encased in a rubber or rubber like jacket 27, which not only covers the toothed peripheral portion of each said impeller. but also has end wall portions 28 and 29 covering the ends of each of said impellers.

The aforesaid jackets may be made of neoprene, Buna N, Hi-Car or of other synthetic rubbers, or of natural rubber, and are bonded to the gear toothed impellers 25 and 26 by means of an effective adhesive. This bonding operation is completed by curing for four hours in a steam jacketed hydraulic press under a pres sure of 2000 pounds per square inch.

. The jacketed portions of the toothed impellers 25 and 26 provide the required structural strength to prevent distortion under pressure, and the rubber jackets provide an abrasion resistant, positive impeller surface contact, both between the two impellers and where their ends approximately engage the end walls of the casing. The peripheries of said jackets are corrugated so as to conform to the individual teeth of the toothed portions of said impellers.

The invention may be applied to intermeshing toothed impellers mounted in various designs of pump casings, and provided with various driving means. In the drawing the casing head 16 and cup shaped cap 21 co-operate to form a totally enclosed oil filled chamber 30, and the driving shaft 31, to which the impeller 27 is axially secured, carries within said chamber a steel cut spur driving gear 32 which is in mesh with a like metal driving gear 33 fixed axially to a driven shaft 34, to which, in turn, is axially secured the driven impeller 26. Said driving shaft 31 extends through, and has its bearing within the casings 11 and 16, whereas the driven shaft 34 extends through and has one of its bearings in said head 16, the other bearing of said shaft 34 being formed by a cylindrical recess 36 in the inner face of said head 11.

It is to be understood that suitable driving means (not shown) will be connected to the part of the shaft 31 which projects outwardly beyond the casing head 11, and that suitable gaskets or packing glands will be provided in the various bearings, where needed. However, where the shafts 31 and 34 pass through the casing head 16 the jacket end portions 29 form an eflicient seal around said shafts to prevent mingling of the water in the pump chamber with the oil in the chamber 30, and the end portion 28 of the jacket of the driving impeller also assists in forming a liquid tight seal around the shaft 31 where it passes through the head 11.

It is to be understood that, where the toothed por- 15 securable to the support on tions of the pair of impellers mesh with each other the intervening elastic jacket layers are maintained under a moderate compression so that a substantially perfect fluid tight seal results between the two impellers, and at the same time the end portions 28 and 29 of the jackets efiiciently seal against leakage past the end surfaces of the impellers, so that, as a result there is made possible a self priming, positive suction lift as well as a positive, high pressure discharge.

In the drawing each pumping gear is shown consisting of a steel spur four vane spider keyed to its shaft and having bonded to it a surface layer (desirably one-eighth of an inch thick) of the character described; but it is to be understood that these details may be considerably varied without departing from the spirit of the claimed invention. Also the intermeshing toothed impellers are shown contoured in such a manner that the rounded, truly semicircular outer end portions of the teeth of each impeller and the correspondingly rounded, truly semicircular root spaces between its adjacent teeth produce an efficient intermeshing of the two impellers, thus positively sealing off back flow between the intermeshing portions of the impellers.

In the operation of the pump the rubber coated peripheral surfaces of the pumping gears impinge firmly in mesh and where they contact with the periphery of the pump chamber, with the result that the vacuum which is created by the rotation of the gears is maintained by the air tight rubber seal. It is this unique feature that makes possible the use of the pump as a self-priming positive displacement pump with capacity in direct ratio to speed.

Since pumpage may be carried along the periphery of the end portions of the pump chamber in the spaces between the impeller teeth at a low velocity, the erosive effect of abrasives in suspension is reduced to a minimum. The adequate thickness and resilient nature of the elastic jackets is also of a definite advantage in handling fluids containing sand, grit, solids and abrasives.

I claim:

1. A rotary gear pump comprising a casing defining a pump chamber having inlet and outlet openings, opposite peripheral portions of the pump chamber being rounded, the pump chamber having flat end walls provided with openings, shafts journaled within said openings of the end Walls for rotation, driving connecting means for said shafts exteriorly of the pump chamber, one-piece toothed impellers mounted upon said shafts within the pump chamber and having their teeth intermeshing, and elastic jackets substantially completely enclosing the impellers and covering the teeth and ends of the same, the ends of the impellers being flat, portions of the elastic jackets covering the teeth of the impellers being compressed between the teeth and said rounded peripheral portions of the pump chamber during rotation of the impellers, said portions of the elastic jackets also being compressed at the intermeshing areas of the teeth during rotation of the impellers, the portions of the elastic jackets covering the fiat ends of the impellers contacting the flat end walls of the pump chamber and slidable thereover, the last named portions of the elastic jackets having openings receiving said shafts and snugly engaging the shafts to form therewith and with the end walls of the pump chamber liquidtight seals.

2. A rotary gear pump comprising a casing defining a pump chamber having inlet and outlet passages, opposite peripheral portions of the pump chamber being rounded, the pump chamber having flat end walls provided with pairs of aligned openings, shafts journaled within the pairs of aligned openings for rotation, gearing connecting said shafts exteriorly of the pump chamber, one-piece metallic toothed impellers mounted upon said shafts within the pump chamber and having their teeth intermeshing, the teeth of the impellers and the root spaces between the teeth being cylindrically rounded, and elastic jackets substantially completely enclosing the impellers and covering the teeth and ends of the same, said ends of the impellers being flat, portions of the elastic jackets covering the teeth of the impellers being compressed between the teeth and said rounded peripheral portions of the pump chamber during rotation of the impellers, said portions of the elastic jackets also being compressed in the areas where the cylindrically rounded teeth contact with the cylindrically rounded root spaces between the teeth durng rotation of the impellers, the portions of the elastic ackets covering the flat ends of the impellers slidably contacting the flat end walls of the pump chamber and having aligned openings registering with said openings of the end walls and receiving said shafts and forming therewith and with the end walls liquidtight seals.

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